Note 5. Investment Partnerships (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Partnership interest, beginning			$ 471,689
Investment partnership gains (losses)	$ (108,614)	$ 5,302	21,908	$ 22,710
Partnership interest, ending	462,894		462,894
Fair Value
Partnership interest, beginning			734,668	776,899
Investment partnership gains (losses)			114,088	(16,313)
Contributions (net of distributions) to investment partnerships			(10,896)	73,500
Increase in proportionate share of Company stock held			0	0
Partnership interest, ending	837,860	834,086	837,860	834,086
Company common Stock
Partnership interest, beginning			262,979	78,917
Investment partnership gains (losses)			92,180	(39,023)
Contributions (net of distributions) to investment partnerships			0	0
Increase in proportionate share of Company stock held			19,807	255,272
Partnership interest, ending	374,966	295,166	374,966	295,166
Carrying Value
Partnership interest, beginning			471,689	697,982
Investment partnership gains (losses)			21,908	22,710
Contributions (net of distributions) to investment partnerships			(10,896)	73,500
Increase in proportionate share of Company stock held			(19,807)	(255,272)
Partnership interest, ending	$ 462,894	$ 538,920	$ 462,894	$ 538,920